Partial amino acid sequence of rat pre-prolactin

Area of Science:

• Molecular Biology
• Biochemistry
• Endocrinology

Background:

• Prolactin is a key hormone regulating reproduction and lactation.
• Understanding prolactin precursor structure is crucial for deciphering its synthesis and regulation.

Purpose of the Study:

• To elucidate the N-terminal sequence of rat pre-prolactin.
• To analyze the structural features of the prolactin precursor.

Main Methods:

• Cell-free synthesis of rat pre-prolactin using pituitary mRNA.
• Radioactive labeling with [4,5-3H]leucine and [35S]methionine or [35S]cystine.
• Amino acid sequence analysis of the synthesized precursor.

Main Results:

• Successfully synthesized and labeled rat pre-prolactin.
• Identified a 29-amino acid N-terminal extension to the prolactin sequence.
• Determined the positions of leucine, methionine, and cysteine residues within the precursor sequence.
• Observed significant sequence similarity between rat pre-prolactin and other known protein precursors.

Conclusions:

• Rat pre-prolactin possesses a distinct N-terminal leader sequence of 29 amino acids.
• The identified precursor sequence shares homology with other secreted protein precursors, suggesting conserved processing mechanisms.